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Prius 2017 prime trunk light not working

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by yoyoman, Aug 2, 2021.

  1. yoyoman

    yoyoman Active Member

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    I have just found out that my trunk light is not working this morning. Checked the bulb and it’s good. Can anyone check which fuse is controlling the trunk light?
     
    #1 yoyoman, Aug 2, 2021
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    I’d first try replacing the “good” bulb; they’re a couple of bucks apiece.

    if problem persists you can say “I told you so”, but hey, doesn’t hurt to try, and worst case, you’ve got a spare bulb for future.
     
    #2 Mendel Leisk, Aug 2, 2021
  3. yoyoman

    yoyoman Active Member

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    I did replaced with a new bulb and still not working . Check the voltage and only getting 1V at the bulb connector. .. should be 12V. Now I’m wondering if the trunk release switch is bad??
     
    #3 yoyoman, Aug 2, 2021
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Ah ok.
     
    #4 Mendel Leisk, Aug 2, 2021
  5. Hidyho

    Hidyho Senior Member

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    Stupid question, but did you check the switch on the light and make sure you didn't accidentally turn it off?
     
    #5 Hidyho, Aug 2, 2021
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  6. yoyoman

    yoyoman Active Member

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    I did check the switch.

    For some reason, just not getting voltage with the trunk open up. Any idea how to pop the plastic cover snap onto the composite trunk ?
     
    #6 yoyoman, Aug 2, 2021
  7. sam spade 2

    sam spade 2 Senior Member

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    Another probably stupid question:
    Do the headlights or parking lights have to be ON for that light to work ?

    Then......before you go to a lot of trouble chasing the voltage, check the ground side.
     
    #7 sam spade 2, Aug 3, 2021
  8. yoyoman

    yoyoman Active Member

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    I have tried to leave the headlight on and opened the truck. Still no voltage. I think I’m going to have to take the panel off. Does anyone know how to pop it open?


    Another thing I have tried. I have my POS voltmeter probed at the bulb connector (plus side) and NEG probed to the body. I’m getting 12V. Seem like there is a switch is not working.
     
    #8 yoyoman, Aug 3, 2021
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Wouldn’t you see no volts, if there was a problem?
     
    #9 Mendel Leisk, Aug 3, 2021
  10. yoyoman

    yoyoman Active Member

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    Seem like the pos wire is getting 12v at the connector but the neg wire is not grounded.. it’s weird.
     
    #10 yoyoman, Aug 3, 2021
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Ah, gotcha, no continuity between neg wire and car body. Could be the smoking gun.


    (First read of your last post, I thought “pos” was an acronym. :ROFLMAO:)
     
    #11 Mendel Leisk, Aug 3, 2021
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  12. burrito

    burrito Active Member

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    You just now made realize that it wasn't!
     
    #12 burrito, Aug 3, 2021
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  13. sam spade 2

    sam spade 2 Senior Member

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    No, it sounds like a GROUND is not working.
    Or that it operates from a switched ground and not switched positive.
     
    #13 sam spade 2, Aug 4, 2021
  14. road2cycle

    road2cycle Active Member

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    The trunk light socket assembly pries right out of the side panel (at least that’s how it is on the 2021). Just be careful since the wire harness behind there is fairly short. I would remove the wire harness plug and check it and the light assembly contacts for corrosion/oxidation/loose connections/etc. You could also probe directly across the wire harness connector for 12V with the trunk open to verify voltage is good up to that point.
     
    #14 road2cycle, Aug 4, 2021
  15. yoyoman

    yoyoman Active Member

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    I have taken the assembly out and disconnected. Both male and female connector are like new. Probe the positive and negative at the connector and get no 12v. However, I did get 12v when probing the positive connector side with a voltmeter and probing negative to any car chassis. Seem like the negative wire at the connector is disconnected somewhere.

    I need to find out where is the switch that turn on the trunk light after releasing the trunk.
     
    #15 yoyoman, Aug 5, 2021
    Last edited: Aug 5, 2021
  16. sam spade 2

    sam spade 2 Senior Member

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    OR that light works by switching the negative side.
    Almost all of them used to work that way.
     
    #16 sam spade 2, Aug 5, 2021
  17. yoyoman

    yoyoman Active Member

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    I have popped the panel off this morning.

    Wiggle the exposed connectors and found 1 was loose. Took it out and plugged-in back. Then said the magic word “Abracadabra”. My trunk light is back to business again.

    IMG_0741.jpg
     
    #17 yoyoman, Aug 6, 2021
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  18. Mendel Leisk

    Mendel Leisk Senior Member

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    And it was the connector at the hatch lock, lol.
     
    #18 Mendel Leisk, Aug 7, 2021
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